Gasoline
 

what is the preferred gasoline for 2018 grand sport?

1. A "Top Tier" brand, which has a higher level of detergents to help keep the engine and fuel system cleaner. Most of the major brands are Top Tier, you can Google it and print the sheet.

2. 93 octane if you can get it, 91 will work fine with just a very slight performance drop per Tadge. I don't like 10% ethanol but in most areas you have no choice, the engine will be fine on it.

93 ethanol free = $3.48/$3.39/gal at the two stations near me. my cars can sometime sit for months/years and I prefer ethanol free to adding Stabil. I kept it in a Z06 that in 10 years only went 2366 miles, never a fuel system problem and its last drive was a 120 mile trip to the trade-in dealer in March. Also used (and don't think I've seen an ethanol-gas pump at the marinas) in my boat's mercury 5.7 V8.

I use a Top Tier 93 octane in mine. I near the house I get Exxon 93 ethanol free.

There is no perfered brand.

Use the highest octane rating available to you.

Use ethanol free if you can. (most people don't have that choice)

Use top tier listed brands. (or not, it really doesn't make that much difference...)

93 octane wherever I find it.

I use mostly Top Tier but also less expensive 93 octane from time to time. At Sam's Club their 93 octane often ~$0.40 gallon cheaper.

Use of GM Recommended Fuel Additive:
The Owner's Manual says if not using Top Tier adding the GM recommended fuel additive at each oil change can help.
Quoting: "If TOP TIER Detergent Gasoline is not available, one bottle of GM Fuel System Treatment Cleaner added to the fuel tank at every engine oil change, can help."

I was buying the GM recommended gasoline additive and using every oil change as they suggest. However it was getting expensive and now they don't list the GM part number so hard to buy on Amazon! Looked at the SDS (Safety Data Sheet) of it and Techron from Chevron. Techron is the additive many Top Tier gasolines used and/or pay Chevron a license for their patent. The GM and Techron SDS appeared to be the same and the GM bottle is identical in appearance so could be bottled for them by Chevron.

The main reason I use it is that both products say they will dissolve sulfur on the fuel level sensors. Top Tier had nothing to do with sulfur. All gasoline have it and the amount "should be low" as it's removed in the refining. However some crude oil can have 3% or more! The EPA has a new lower standard in 2017 of 10 PPM. Did the refiner get it all that low? Gasoline in our area comes in by pipeline so Sam's gas is the same as all others until the additives are put in when the delivery tank truck is filled! So sulfur is the same.

So even if using Top Tier, fuel senders failures can occur. In fact if storing Vettes for the winter it's now suggested only filling the tank ~1/3 to avoid the sender being immersed in gasoline during storage where the gas is not sloshing around.

There are a number of posts about fouled C7 senders. To remove and replace the sender the tanks have to be dropped. That requires dropping the drive train. Recall a post where the owner was horrified when he saw his drivetrain on the garage floor! In another post the owner had his erratic sender reading fixed by a dealer using two bottles on the GM gasoline additive listed in the Owner's Manual. He was charged $100 but it solved the issue. Probably out of warranty or the dealer would much rather charge GM for a replacement! Must be expensive! :lol:

Adding a ~$5 container of fuel injection cleaner every oil change is a cheap precaution to assist with sulfur issues and make up for my periodic use of none Top Tier gas at Sam's Club! In fact just changed oil and added a container of Techron at the last gasoline fill.

Costco is Top Tier and has 93 octane here in Texas.

I use any brand top tier gas with 91 octane, and up. As far as the non-ethanol I don't think that's necessary IMHO. The engine is designed to run ethanol. I did a test with my C6 running a tank of ethanol free gas. The extra mpg's didn't make up for the cost of the gas.

Yep apparently all over but the closest COSTCO is in Myrtle Beach ~60 miles away so we are not members. But when we visit daughter in OH we do go with her and it is better in many ways than Sam's BUT not worth a 60 miles trip! In the summer we also will NOT go to Myrtle Beach-too crowded! :lol:

We are lucky up here in Ontario, as Costco is not only the cheapest gas around, but it's premium is ethanol free. I haven't run ethanol enhanced gas yet in my C7 so I'm not sure how much MPG difference there will be.

I add a bottle of injector cleaner every moth as a habit.

From your Owners Manual:

Top Tier Gasoline vendors
https://toptiergas.com/licensedbrands/

Wow, a lot of you are lucky. The highest quality fuel (at a gas station) I can find around here is 91 octane with ethanol. I didn't want 91 octane or ethanol so I buy Sunoco 93 octane in 55 gallon drums. Definitely not the most convenient.
https://cimg2.ibsrv.net/gimg/www.cor...a0cc780c35.jpg93 octane

Where is "around here"?
Nothing in your profile except USA.

A lot of us have similar problems.

Driving home from AZ, there were a lot of places, still relatively low altitude, where the highest we could find was 90.

The same as for the base stingray (since both share the exact same engine).

I can run 'em all according to my 2017 Owner's Manual; 88, 87, 89, 93 with the exception of E85, and diesel fuel.

Usually 87, as it's approved for my 2017 C7, and saves a lot of jack! Car runs great!

You'd be advised to read your Owner's Manual too.


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Hmm, YOU should read the Owner's Manual more carefully! This is a direct quote of the short (in up front summary) and long statements;

"Use premium 93 octane unleaded gasoline in your vehicle. Unleaded gasoline with an octane rating as low as 87 may be used, but it will reduce performance and fuel economy."

Long Version In Back:
"For the LT1 6.2L engine, premium unleaded gasoline meeting ASTM specification D4814 with a posted octane rating of 93 is highly recommended for best performance and fuel economy. Unleaded gasoline with an octane rated as low as 87 can be used. Using unleaded gasoline rated below 93 octane, however, will lead to reduced acceleration and fuel economy.
If knocking occurs, use a gasoline rated at 93 octane as soon as possible, otherwise, the engine could be damaged. If heavy knocking is heard when using gasoline with a 93 octane rating, the engine needs service."

Note: I highlighted key words in BOLD!

The LT1 has a number of knock (preignition) sensors (suggest you google both words in bold.) I recall it has 6 perhaps more. You will probably never heard a knock (unless you drive to Mexico where the gas can be less than 87 octane where you might as your engine is being destroyed!)

When knock is sensed, it sends a signal to the computer that will automatically reduce the timing and if needed also richen the mixture to stop the preignition so the engine isn't damaged!

That cuts down on power and makes gas mileage worse with a rich (higher fuel to air ratio) mixture! That makes the "saving money" choice you think you are making - wrong!

Yep you may think the engine is running fine but that is happing with reduced power while wasting that "cheap" gas! :yesnod: